Encountered in the study can not use the array map to delete files, error is the callback function unlink there is a problem ~ please help! Thank!

$map_dir_arr=glob('cel\*');array_map('unlink',$map_dir_arr);rmdir('ce1');

The error is:
Notice:use of undefined constant unlink-assumed ' unlink ' in D:\DEMO\study\document\doc6.php on line 44

Line 44 is the second line in the statement.
Also encountered a lot of problems: I listen to the free video of the backing net, is too poor/(ㄒoㄒ)/~~, inside the teacher dozen code does not error, and I hit the same error, because the video is 11, and now the version has been changed?

Originally thought is no quotation mark reason, the result adds also error, the video teacher did not add the quotation marks, the younger brother beginner, please each road immortal helps, by the way wishes everybody Happy New Year ~ ~ ~

Reply content:

$map_dir_arr=glob('cel\*');array_map('unlink',$map_dir_arr);rmdir('ce1');

The error is:
Notice:use of undefined constant unlink-assumed ' unlink ' in D:\DEMO\study\document\doc6.php on line 44

Line 44 is the second line in the statement.
Also encountered a lot of problems: I listen to the free video of the backing net, is too poor/(ㄒoㄒ)/~~, inside the teacher dozen code does not error, and I hit the same error, because the video is 11, and now the version has been changed?

Originally thought is no quotation mark reason, the result adds also error, the video teacher did not add the quotation marks, the younger brother beginner, please each road immortal helps, by the way wishes everybody Happy New Year ~ ~ ~

function MyFunction ($v)
{
Return ($V * $v);
}

$a =array (1,2,3,4,5);
Print_r (Array_map ("MyFunction", $a));
?>

Unlink method not written??

